Study On Luxury Transpiration Of Green Pepper In Solar Greenhouse Under Water And Nitrogen Regulation

Transpiration water loss is the main part of crop water consumption.Extraneous transpiration is the water that exceeds the water consumption necessary for plant physiological metabolism,nutrient transport and yield formation.In order to clarify the law of transpiration water consumption of crops and the regulation theory of luxury transpiration,the effects of water and nitrogen regulation on luxury transpiration of green pepper in solar greenhouse were studied.The experiment was carried out in the solar greenhouse of Shenyang Agricultural University for two consecutive years.Three different upper and lower limits of irrigation treatment were set up（W₁:60%～70%;W₂:70%～80%;W₃:80%-90%）,four different nitrogen levels（N₀:0 kg/hm²;N₁:120 kg/hm²;N₂:180 kg/hm²;N₃:240 kg/hm²）,a total of 12 treatments with 3 replicates per treatment.The photosynthetic rate,transpiration rate and stomatal conductance of green pepper in greenhouse were monitored.Identified the influence of the luxury transpiration and disappearing time nodes and calculate the luxury transpiration,analyzed the water and nitrogen on the impact of greenhouse green pepper luxury transpiration,and clear the greenhouse green peppers to maintain water use efficiency is larger,luxury transpiration from hours of stomatal conductance interval.The main conclusions are as follows:（1）Effects of water and nitrogen on photosynthetic characteristics of green pepper in greenhouse.Under low water condition,proper amount of nitrogen fertilizer was more conducive to the improvement of photosynthesis.Water stress can inhibit the transpiration of green pepper,and excessive nitrogen application can inhibit the transpiration of green pepper in the late growth stage of greenhouse.The photosynthetic characteristics of green pepper in greenhouse were inhibited by N₃treatment at full fruit stage and tail fruit stage.Compared with N₂treatment,the decrease of N3W3 was slightly smaller than that of N₃W₁and N₃W₂.Irrigation weakened the inhibition effect of excessive nitrogen application on photosynthetic characteristics of green pepper in greenhouse.（2）Effects of water and nitrogen regulation on luxury transpiration of green pepper in greenhouse.In this experiment,luxury transpiration was found in all water and nitrogen treatments.Luxury transpiration usually appeared from 8 to 10 and disappeared from 12 to 14.Taking the calculated results in 2019 as an example,the luxury transpiration of green pepper in greenhouse was 161.61 g/m²～427.14 g/m²at flowering and fruiting stage,76.38 g/m²～480.64 g/m²at full fruiting stage,23.13 g/m²～285.25 g/m²at fruiting stage.The luxury transpiration decreased gradually with the development of growth period.Under different water treatment conditions,the luxury transpiration of green pepper in each growth period showed the same rule:luxury transpiration of full irrigation>luxury transpiration of moderate irrigation>luxury transpiration of mild irrigation.Under the same nitrogen level,the luxury transpiration under full irrigation was significantly higher than that under deficient irrigation.Nitrogen application had little effect on luxury transpiration of high water treatment,but significantly on luxury transpiration of medium and low water treatment.Nitrogen application significantly increased luxury transpiration of green pepper in flowering and fruiting stage and full fruiting stage.（3）The relationship between luxury transpiration and stomatal conductance of green pepper in greenhouse under water and nitrogen regulation.The stomatal conductance value point was considered as the optimal stomatal conductance when the transpiration rate and photosynthetic rate of green pepper in greenhouse grew at the same speed as the fitting curve of stomatal conductance change.The stomatal conductance value at this point was the critical point for the generation of luxury transpiration,and when the stomatal conductance value exceeded,luxury transpiration began to occur.Previous studies showed that the optimal stomatal conductance was the same under different water treatments.In this study,the optimal stomatal conductance was studied under different nitrogen levels.The results showed that the optimal stomatal conductance was almost the same under different nitrogen levels.Under N₁treatment,the average of the optimal stomatal conductance was 383μmol m^-2s^-1.Under N₂treatment,the average of the optimal stomatal conductance for two years was 339μmol m^-2s^-1.Under N₃treatment,the average of the optimal stomatal conductance in two years was 316μmol m^-2s^-1.Therefore,when the stomatal conductance of green pepper in greenhouse was in the range of 300-400μmol m^-2s^-1in autumn and winter,the increase rate of photosynthetic rate and transpiration rate of green pepper in greenhouse was basically consistent.Is the optimum stomatal conductance range of green pepper in greenhouse.The research results provide technical support for improving the theory of crop transpiration regulation,improving crop water use efficiency and drought resistance and disaster reduction.